Candidatus

Candidatus (Latin for candidate of Roman office, named after the white gown worn by Roman senators) is in scientific classification a component of the taxonomic name for a bacterium that cannot be maintained in a Bacteriology Culture Collection. It is an interim taxonomic status for noncultivable organisms. An example would be "Candidatus Phytoplasma allocasuarinae". This can be abbreviated to "Ca. Phytoplasma allocasuarinae". Candidatus status may be used when a species or genus is well characterised but unculturable. Nowadays much information is obtained by 16S ribosomal RNA or even near-complete genomes with modern metagenomics techniques.